The present invention relates to an energy management system. More particularly, the present invention relates to a variable base load demand side energy management system for both stand-alone and networking applications.
In the past, utility companies that provided electricity to consumers charged a fixed cost of electricity per kilowatt hour. The cost of the electricity did not vary during different periods of the day. The utility companies averaged out the cost of electricity during the day to establish the price charged. As a consequence of this fixed rate pricing, a company which operated mostly at night was probably paying too much for its electricity. On the flip side, a retailer operating only during the day was probably paying too little.
Due to the worldwide electric privatization and deregulation movement, many utility companies are now starting to vary the rate charged for electricity during the course of a day. This is referred to as real-time pricing. For example, on a hot summer day in the city when a high amount of air conditioning is being used, at 12:00 PM the price of electricity charged to the customer could be 3 cents per kilowatt-hour. At 1:00 PM, the electricity demand increases due to increasing heat and air conditioning use, and the price climbs to 4 cents. By 3:00 PM, the demand is at its peak and the price has gone up to $1.06.
In response to this sharp increase in price, a consumer of electricity may wish to decrease the amount of electricity that he consuming in order to cut down on costs. A consumer of electricity could be an owner of a building, an owner of an industrial plant, a home owner, or any other individual or business purchasing electricity from the utility company. In the past, the consumer typically could reduce his or her demand by turning off loads such as individual lights or pumps. Alternatively, the consumer could reduce the on-time of cyclic loads such as air conditioners. For example, the consumer could raise the thermostat setting to decrease the amount of on-time for the air conditioner. Reducing the on-time of cyclic loads has the effect of reducing the peaks of the consumer""s power usage during the day.
What is needed is a system that allows a user to conveniently and automatically vary his or her xe2x80x9cbase loadxe2x80x9d during the day in response to a changing price of electricity. A xe2x80x9cbase loadxe2x80x9d is a constant load which remains on all day. A base load does not turn off until the facility or the process is no longer needed, unlike cyclic motors and pumps which turn on and off and vary on-time according to the external conditions. Lighting is an example of a base load which exists in almost every commercial or industrial building.
Instead of reducing demand by shutting off lights and other loads, it would be advantageous to have a system which allowed the user to merely reduce the lighting power or other base loads during periods of the day when the electricity usage is most expensive. For example, if the electricity rate is most expensive at 3:00pm, a user could reduce his costs by having a system which automatically dimmed the lights at 3:00 PM, rather than shutting off half the lights in the building.
What is needed is a system that can perform variable base load, demand-side management for energy management and conservation, in all types of commercial, industrial and public sector facilities and areas. What is also needed is a system that can interface and communicate with various proprietary and open protocol automation systems over a computer network in addition to having stand-alone capabilities. What is also needed is a system that can provide control safety algorithms to insure the lamps and ballasts are properly protected. Finally, what is needed is a controller that can has the flexibility to control the lamp loads using a variety of different inputs such as voltage, kW, current, light level, analog and digital inputs from other controllers, and schedules.
The present invention is a system and method for variable base load demand-side energy management. The system of the present invention includes a power reduction device receiving electrical power from an electrical power source and outputting electrical power to a load. A processor outputs a control signal to the power reduction device to decrease the power delivered to the load in response to a rise in the price of electricity and increase the power delivered to the load in response to a decrease in the price of electricity. The processor can do this by receiving a schedule from a user, the schedule including control setpoints for different time periods during the day and/or week. The processor then generates the control signal based on the schedule and the time of day. The processor can also receive real-time price information from the electrical utility company. The processor generates the control signal based on the real-time price information.
The processor can also receive input variables such as voltage, current, light level, and power and can control the power reduction device so as to maintain one or more user specified input variables within a user-specified control band. A user terminal can receive control instructions from a user. The user terminal and processor can be connected to a computer network, and the control instructions sent to the processor over the computer network. This allows a user terminal to control many remote processors over the computer network.
The system of the present invention can control the power delivered to one or more devices located in one or more facilities by sending control signals over various kinds of networks using various communication methods simultaneously, such as a modem, a LAN, or a WAN such as the Internet.